Ocean oxygen levels drop endangering marine life

Katie Ramirez
December 9, 2019

COP25 MADRID, International ocean experts gather to kick-off COP25 Oceans Actions Day at the Ocean and Coastal Zones Climate Action event to deliver concrete recommendations on ocean and coastal climate actions, accelerating progress towards global climate goals.

Some of the oceans' most productive biomes, which support one fifth of the world's wild marine fish harvest, are formed by ocean currents carrying nutrient-rich but oxygen-poor water to coasts that line the eastern edges of the world's ocean basins.

"With this report, the magnitude of the damage that climate change is causing in the ocean becomes a clear focus".

Low levels of oxygen are also bad for basic processes like the cycling of elements crucial for life on Earth, including nitrogen and phosphorous.

The report discovered that oxygen loss is increasingly threatening fish species such as tuna, marlin, and sharks, all individually sensitive to low levels of prolific gas due to their large size and energy needs.

"Deoxygenation will have an impact on biodiversity, on the biomass of commercially important species and on rare rare species". These regions are especially defenseless to even tiny variations in oxygen levels.

Keeping the business-as-usual approach regarding emissions would mean for the world's oceans to lose between 3% and 4% of the oxygen by 2100.

Isabella Lovin, Sweden's minister for environment and climate, wrote in the report: 'Whilst we have known about dead zones in the ocean for many decades, ocean warming is now expected to further amplify deoxygenation across great swathes of the ocean. Communities may have a reduced catch or are forced to spend more to obtain the affected species-impacts that threaten not only nutrient loss but cultural loss.

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It also warns that deoxygenation is altering the balance of marine life, leaving eco-systems in danger of collapse - with the impact 'ultimately rippling out and affecting hundreds of millions of people'.

Ocean life is already battling warmer temperatures, rampant overfishing and plastic pollution.

This week, the World Meteorological Organization said that because of the growth of human-made emissions, the ocean was now 26% more acidic than before the revolution industrial.

"To stop the worrying expansion of oxygen-poor areas, we need to decisively curb greenhouse gas emissions, as well as nutrient contamination from agriculture and other sources".

The IUCN report also found that pollution around shorelines was having a notable effect on oxygen levels, with fertilizer and agricultural runoff promoting more algae growth, which in turn depletes oxygen as it decomposes. "The delicate balance of marine life is thrown away into [chaos] as the warming ocean loses oxygen", Aguilar added.

World leaders will meet in Marseille in June for the IUCN World Conservation Congress.

IUCN's senior marine science adviser Dan Laffoley said that ocean oxygen depletion is threatening marine ecosystems and is now under stress from ocean warming and acidification.

Policy makers are now negotiating at the COP25 climate summit in Madrid to ratify a comprehensive settlement for the 2015 Paris agreement.

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